1. FIELD OF THE INVENTION
This invention relates generally to pavement markers, and is particularly concerned with pavement markers of the type having a shell-like body of light transmitting material with a reflective wall formed with retrodirective reflector elements, and which is reinforced with a filler material, such as epoxy resin.
2. DESCRIPTION OF THE PRIOR ART
It has become common practice to delineate traffic lanes and the edgs of roadways by pavement markers having retrodirective reflector elements, such as cube corner reflex reflector elements, for reflecting the lights from vehicles travelling over the roadways at night. Such pavement markers are superior to painted strips on the roadway since, uner poor weather conditions, painted strips on the roadway are not visible.
U.S. Pat. Nos. 3,332,327 and 3,409,344 disclose pavement markers having planar reflective walls formed on their inner surfaces with cube corner reflector elements. The reflective walls form part of a shell-like body of synthetic resin or the like, which, when installed on the surface of a roadway, is filled with a filler material such as epoxy resin to reinforce the shell-like body against external forces imposed particularly by vehicles travelling over the roadway. The impact forces of vehicles are sometimes great enough to rupture the shell-like body of such pavement markers, particularly when a void occurs in the filler material. The flat, planar walls of the shell-like body rupture more easily when a void occurs in the filler adjacent to the wall of the shell-like body. Voids are particularly difficult to detect when the void occurs adjacent to the reflective wall, which is the wall that usually receives the greates impact. The cube corner reflector elements formed on the inner surface of the reflective wall renders it impossible to visually detect a void behind the reflector elements.